London has become so hard to navigate in the wake of the terrorist attacks, I'm loathe to recommend anything at the moment. I left my house in Shepherd's Bush at 5.45pm last week and didn't get to the Donmar Warehouse until 7.20pm, by which time Mary Stuart had been playing for 20 minutes. (It's normally a 30-minute journey.) My wife and I had to sit in the bar, watching the play on close circuit television, for a further 20 minutes before being forced to stand at the back of the Upper Circle for the remainder of the first half. It was a truly miserable start to the evening.

Incredibly, though, it was worth the aggravation. Schiller's play about the battle between Elizabeth I and Mary, Queen of Scots, is a riveting piece of political theatre, a penetrating examination of the toll taken by high office on the individual office-holder. In spite of its title, the real subject of the play isn't Mary but Elizabeth and the question it poses is this: How far should our political leaders be allowed to go in sacrificing principles of justice to the national interest? On the face of it, Schiller, who was a 19th Century German liberal, seems to be on the side of justice, but he's intelligent enough to realise that a rigid adherence to the law, particularly international law, is often impractical. The issue then becomes: Given that our political leaders shouldn't be held to ordinary moral standards, how are we to distinguish between integrity and corruption? Is there a yardstick by which they should be judged other than the national interest? Or, to put it another way, was Elizabeth a hero or a villain?

As with Don Carlos, Schiller's primary interest is in the sacrifices an individual must make to succeed in affairs of state--the part of their humanity they must snuff out--and the fact that the two political leaders in Mary Stuart are both women brings this issue into sharp relief. There's a poignant scene in the first half in which Elizabeth expresses her irritation at having to marry for political reasons. If she had her way, she tells her confessor, she'd remain a virgin all her life and concentrate exclusively on running the country. Mary, too, has made her private life subordinate to what she sees as her higher calling, having paid a man to murder her second husband and then married his murderer, all in the name of political advancement.

If all this sounds rather high-minded, don't be put off. There are plenty of low pleasures to be had here, principally the spectacle of two powerful queens engaged in a battle to the death. As played by Harriet Walter and Janet McTeer, they indulge in a high-octane bitchfight that reminded me of Sigourney Weaver's hand-to-hand combat with the alien queen in Aliens. The most powerful scene in the play occurs when the two of them actually meet on the hunting field and almost end up scratching each other's eyes out (Elizabeth has to be physically restrained by her courtiers who effectively say, "She's not worth it.") Mary Stuart isn't quite as good as last year's production of Don Carlos--easily the best play of the year--but it's worth braving a few terrorist bombs for. It'll almost certainly transfer to the West End, but I doubt these two leading ladies will go with it, so catch it now if you can.

The Gruffalo, by contrast, isn't worth bothering with even if you happen to live next door to the Criterion. Based on the charming children's book by Julia Donaldson and Axel Scheffler about a plucky little mouse, it's an insipid, uninspired piece that barely lasts 45 minutes. I took my two-year-old daughter, thinking this would be a perfect way to introduce her to the theatre, but she immediately homed in on the production's biggest flaw, namely, the very un-mouse-like woman playing the central character. "Where's the mouse?" she asked, as Alice Parsloe held her arms out in front of her and bit her bottom lip. "There she is," I said, pointing at the performer. My daughter looked intently at the stage, then turned back to me with a puzzled expression: "Where's the mouse?"

Part of the problem is that the costumes are so minimal. Parsloe has ears and a tail, but that's about it, and when the Gruffalo finally appears, he looks like he's got one of those mops on his head with strips of J-cloth-like material, rather than thin rope. I'm intending to put on my own version using my daughter's finger puppets and, however feeble it is, at least the production values should be considerably higher.